Getting system uptime in iOS/Swift - ios

Question

Is there a way to get system uptime in iOS (using Swift)? What I need is to measure time without having to worry about the user changing the time. In Android there's a elapsedCurrentTimeMillis() that returns the number of milliseconds since boot, but now I need something like that for iOS. There's an accepted answer here Getting iOS system uptime, that doesn't pause when asleep but that's for Objective C and I need it for Swift and I don't know how to convert it.

Answer 1

As you ask for a pure-Swift solution, I converted the ObjC code from the answer you mentioned Getting iOS system uptime, that doesn't pause when asleep.
func uptime() -> time_t {
var boottime = timeval()
var mib: [Int32] = [CTL_KERN, KERN_BOOTTIME]
var size = strideof(timeval)
var now = time_t()
var uptime: time_t = -1
time(&now)
if (sysctl(&mib, 2, &boottime, &size, nil, 0) != -1 && boottime.tv_sec != 0) {
uptime = now - boottime.tv_sec
}
return uptime
}
// print(uptime())
To make it a bit prettier, we can use sysctlbyname instead of sysctl:
// var mib: [Int32] = [CTL_KERN, KERN_BOOTTIME]
sysctlbyname("kern.boottime", &boottime, &size, nil, 0)

Answer 2

This is a solution in Swift 4.
var boottime = timeval()
var size = MemoryLayout<timeval>.stride
sysctlbyname("kern.boottime", &boottime, &size, nil, 0)

Answer 3

Updated for Swift 5 and straight from ADF post here:
func bootTime() -> Date? {
var tv = timeval()
var tvSize = MemoryLayout<timeval>.size
let err = sysctlbyname("kern.boottime", &tv, &tvSize, nil, 0);
guard err == 0, tvSize == MemoryLayout<timeval>.size else {
return nil
}
return Date(timeIntervalSince1970: Double(tv.tv_sec) + Double(tv.tv_usec) / 1_000_000.0)
}
"Be aware that this time will change if the system clock changes, that is, the value is the boot time relative to the current system clock."

Answer 4

You can call ObjC code from Swift:
print(SystemUtil().uptime());
Write a ObjC class like the accepted answer you mentioned: Getting iOS system uptime, that doesn't pause when asleep.
SystemUtil.h for interface:
#import <Foundation/Foundation.h>
#interface SystemUtil : NSObject
- (time_t)uptime;
#end
SystemUtil.m for implementation:
#import "SystemUtil.h"
#include <sys/sysctl.h>
#implementation SystemUtil
- (time_t)uptime
{
struct timeval boottime;
int mib[2] = {CTL_KERN, KERN_BOOTTIME};
size_t size = sizeof(boottime);
time_t now;
time_t uptime = -1;
(void)time(&now);
if (sysctl(mib, 2, &boottime, &size, NULL, 0) != -1 && boottime.tv_sec != 0) {
uptime = now - boottime.tv_sec;
}
return uptime;
}
#end
And don't forget to include a <Project>-Bridge-Header.h with the following content so that you can use the ObjC class from Swift (<Project> is your project name):
#import "SystemUtil.h"